The present invention relates to an improved engine prelubrication pump which operates with an internal combustion engine; and, in particular, to an oil pump which is driven by a starter motor armature drive shaft and which pump includes an internal vent for improved pump and motor durability. The invention is also applicable to stand alone or supplemental prelubrication pumps.
Generally, the fluid pump of the present invention is an improvement over pumps shown U.S. Pat. Nos. 4,553,512, 4,875,551 and 4,502,431. These pumps are used to lubricate the engine prior to the initial phase of the cranking of the starter motor to turn over an engine. Typically, oil is used as a lubricant to allow engine parts to slide freely and easily with reduced friction. Notwithstanding the use of lubricants having high lubricity there continues to be abrasive wear between metal parts in internal engine components such as the turbocharger, camshaft, crank shaft and rocker assembly, for example. It has been known for some time that the greatest wear on internal engine parts is at the commencement of ignition cranking and engine start-up. During that time, there is insufficient oil pressure in the engine to provide lubrication to the various parts throughout the engine. Accordingly, for these initial moments during start-up, there is metal rubbing against metal without a sufficient lubricant interface so that deterioration in the internal engine components takes place over time.
A particularly important solution to this problem was provided by a prelubrication system disclosed in U.S. Pat. No. 4,502,431 in which oil is introduced in the engine prior to cranking and start-up. The starter motor is utilized as the means for powering the pump to provide prelubrication. In that system, the starter motor armature shaft is connected to the pump""s pumping gears which are rotated to provide the pumping action to the engine to prelubricate prior to the starter motor""s solenoid engaging the starter to crank the engine for start-up. One particular embodiment of the starter motor and pump combination is disclosed in U.S. Pat. No. 4,553,512 which is incorporated herein by reference.
The present invention provides a similar pump assembly as that disclosed in U.S. Pat. No. 4,553,512 to provide a selectable means for either prelubricating the engine or pumping the oil out for a quick efficient oil change. This is particularly useful to large fleet operators of vehicles which require frequent oil changes.
Accordingly, it is an object of the present invention to provide a pump mechanism to pump the oil out of an engine sump without having to open the sump""s oil plug. It is a further object of the invention to provide a seal bore vent to the pump inlet to minimize the oil pressure at the seal during all modes of operation. It is a further object of the invention to provide a prelube pump having a valve which is selectively operable in the prelubrication mode as well as an oil exchange mode either from the engine compartment and/or from a time delayed mechanism.
The present invention provides a gear-type pump which is integrated to the starter motor of a vehicle. As disclosed in the aforementioned prior art, the base portion of the pump generally comprises the back or bearing end of the starter motor and includes a sealed opening through which an extended armature shaft can be mounted to rotate or power the pump gears. A pump housing is integrally formed on the base plate which provides a cavity in which the pump gears are mounted and includes an inlet and outlet port. In addition, the present invention provides a seal bore vent to the pump inlet which uses a passageway from the pump inlet into the armature shaft or pump seal bore to minimize the oil pressure at the seal during all modes of operation. This vent relieves pressure from the seal which seals the pump cavity from the motor cavity. In this way, the pump and motor are further protected from damage and their longevity enhanced. This is especially the case when a valve selector and port are provided in the pump as set forth in one of the embodiments hereof.
Additionally, the invention may include an additional port for operation of valve mechanism to permit the oil to be pumped and bypassed to the outlet port in normal operation. By rendering the valve xe2x80x9cineffective,xe2x80x9d oil can be pumped to the outlet port for either prelubrication or for changing the oil of the vehicle.
Other advantages of the present invention will become apparent from a perusal of the following description of a presently preferred embodiment taken in connection with the accompanying drawings.